/Engine/Plugins/FX/Niagara/Source/Niagara/Classes/NiagaraSystem.h
Helper method to handle when an internal variable has been removed. Resets any downstream dependencies in the emitters or exposed variables.
void HandleVariableRemoved ( const [FNiagaraVariable](API\Plugins\Niagara\FNiagaraVariable) & InOldVariable, bool bUpdateContexts )